Blood damage caused by flow shear can cause thromboembolic complications that seriously limit the performance of a broad range of cardiovascular hardware including prosthetic valves, bypass pumps, and assist device. An attractive way to mitigate the adverse effects of high shear stress in cardiovascular hardware is to use miniature, surface-integrated passive flow control elements (e.g., vortex generators, riblets, dimples, etc.) which have already been exploited in mechanical and aerospace applications. The focus of this R21 proposal is to explore the effectiveness of relatively simple, integrable passive flow control elements to achieve significant control of blood flow within cardiovascular systems with the objective of minimizing blood damage and flow losses by controlling the evolution of coherent large-scale shear-inducing eddies in order to increase dissipation of high Reynolds stresses, or suppression and reduction of flow separation. We propose to demonstrated the feasibility of this approach in an idealized bileaflet mechanical valve test-bed where passive flow control will be implemented using miniature vortex generators in order to alleviate the instantaneous shear stresses of the pulsatile flow in between the leaflets and thereby significantly reduce shear-induced blood damage. Our preliminary work in this effort has already demonstrated reduction in turbulent stresses and diminution of blood coagulation in a steady flow model. In this study, we will build on these preliminary findings by optimizing various passive flow control configurations (including conformable protrusions) on an idealized valve test-bed and validate the effectiveness of the optimized configurations in an in vitro pulsatile blood loop. We anticipate that this research will provide the basis for a later submission of an R01 proposal aimed at a fundamental investigation, modeling, and controlling platelet activation/blood damage/thrombus formation for managing blood flow in cardiovascular hardware thus paving the way towards the realization of new design paradigm for cardiovascular hardware in which blood flow losses and damage are mitigated and controlled by novel, integrated passive flow elements. PUBLIC HEALTH RELEVANCE: Blood damage caused by flow shear causes thromboembolic complications in prosthetic heart valves. We investigate a new technology to reduce shear concentrations in blood flows and thus enable the development of a new generation of cardiovascular devices.